Hi Dinh,
1> What is difference between Connection cost and Setup Fee in DID tab ?
Connect Cost: 	Connection fee to charge customer minimum when their call will be connected.

2> What is Initial Increment and Increment in DID tab ?
Initial Increment: It specify cost which you have to take when call is initiate. It's kind of minimum amount you want to take from customer if call active for fewer seconds then mentioned in Initial Increment.

3> How many server will need on production system ?
That depends on your requirement. You can discuss your need with sales team.

4> How many IP addressed and Interface will have on production system ?
It again depends on your requirement, we have generally single profile works on a single interface but if your requirement is different then should use multiple also.

5> Do these servers have HA mode ? do they use Virtual IP address for this feature  ?
We provide different types of cluster setup. HA cluster is one of them. you can check for same with sales team. Yes. In HA, we use virtual IP.

6> What is LC charge/Min in Account tab ?
It's cost applicable on SIP to SIP call (Local Calls). i.e. local calls between the customers of the same server using sip devices.

7> What is refill coupon ? what is difference between Quantity and Amount ?
Refill Coupon is used by customer to refill their account. You can check by login in customer account. Quantity is no. of coupon you want to create. Amount is Refill Amount for Coupon.

8> What is Strip and prepend in Termination rate ?
If you want to remove any starting digits of dialed number belongs to that termination rate then you can put it as Strip. Simillarly, If you want to add then use Prepend. It work as dialled number translation.

9> I saw there are 3 place where we can put charging value : in DID , Rate group , Originate rate and termination rate , can you help to explain for the difference among them and which situation will use for each of them .
-> Charge for DID is Only applicable when any incoming call comes on that DID.
-> Charge in Rate group and Origination rate. Those both works together almost. As those, both are for your customer. System will give priority to Origination rate so it would recommend to use that charge.
-> Charge in ter. rate belong to your Gateway provider. You should put rate which you are paying to your provider for particular code there.

10> We need an API from ASTPP to take all information on invoice like details of customer , charging cost and time ...
Please check for that with sales team at [email protected]

11> We need a capacity for charging cost on minutes block (example 1000 minutes) with a fixed price and change to next minutes block with another price .
Again, Please check for that with sales team at [email protected]

12> We need  only Signaling go thought ASTPP server and RTP will bypass , so please make sure ASTPP system will transparent initial Invite message without modify anything specially Media IP from our softswitch in SIP header .
-> We have enabled that things on ASTPP side in profile: "inbound-bypass-media = true". So we are not doing anything with RTP now. You have to check and manage with your softswitch and telco.